This invention relates to a fabric softening composition which includes a mixture of a quaternary ammonium functional siloxane and at least one surfactant which is anionic. The invention is also directed to detergent laundering products containing the fabric softening composition.
Solid detergent formulations are sold in powder or granular form. A disadvantage of solid detergents is that, on account of the hygroscopic nature of individual raw materials of the formulation, the solid detergent shows a pronounced tendency towards caking or clumping in the presence of small quantities of moisture. This does not make the detergent unusable, however, because the effect of the individual components of the detergent remain intact even after clumping or caking in the presence of moisture. However, the appearance of the detergent in most cases is diminished. As a result, there has been a desire to develop liquid detergent compositions for convenience in lieu of conventionally formulated solid detergent compositions. The liquid detergent allows for use of lower washing temperatures inclusive of cold water laundering. Granular detergents have not fully adapted to such variations because of weaknesses in respect of dissolving speed, insolubility, and cleaning efficiency. Due to such problems of caking and the slowness of solid and granular detergents to dissolve, trends in detergent manufacture have leaned toward the liquid detergent. Such detergents usually include one or more anionic, nonionic, and cationic organic surfactants, water, brightening agents, hydrotropes, enzymes, soil suspending agents, bleaches, pH modifiers, and solvents. It is not uncommon to also include antifoam formulations as a part of the detergent package. Such systems may be built or free of builders.
A fabric softener, on the other hand, often contains a dilute solution or dispersion of a quaternary ammonium derivative used to treat fabrics in the final rinse cycle of a laundering process in order to make the fabrics feel softer. In addition to softness, fabric softeners are known to also provide static control. Because of the affinity of quaternary ammonium compounds for negatively charged surfaces, their single largest market has been as fabric softeners. Commercial fabric softeners generally include about a four to eight percent dispersion of quaternary ammonium compound which is added to the rinse cycle of the washing process. In some cases, a fatty acid stearate is added to modify the handle. The quaternary ammonium compound can also be applied to a nonwoven sheet or a polyurethane foam which is added with wet clothes in a dryer. Such sheets contain a fatty amine or a fatty acid ester which allows the quaternary ammonium compound to transfer from the sheet to the clothes in the dryer during the drying cycle. Recently, there have been devised combined detergent and softener formulations which allow introduction of all additives in the wash cycle.
A basic distinction should be drawn between a rinse cycle softener and a wash cycle softener. As noted hereinabove, the rinse cycle fabric softener is a liquid dispersion of a quaternary ammonium compound which is added separately to the rinse liquor during the rinse cycle of the laundering device. A wash cycle fabric softener in contrast typically contains the quaternary ammonium compound which is mixed in with the laundry detergent and added to the wash liquor by the homemaker before initiation of the wash cycle of the fabric laundering device.
Quaternary ammonium functional siloxanes are not new in the art. For example, in United Kingdom Pat. No. 1,549,180, published July 25, 1979, there is described certain fabric conditioning compounds which are dialkylquaternary ammonium terminated linear polydimethylsiloxanes. The compounds of the present invention, in contrast, are monoquaternary ammonium functional polydimethylsiloxanes, and are trialkylsiloxy terminated rather than dialkylquaternary ammonium terminated as the materials in the '180 patent. United Kingdom Pat. No. 1,006,729, published Oct. 6, 1965, is directed to certain surfactants which are trialkyl mono(polysiloxy) ammonium chlorides. However, the compounds of the present invention can be distinguished in that the compounds are dialkyl di(polysiloxy) ammonium chlorides, as well as some species which are monoalkyl tri(polysiloxy) ammonium chlorides. Thus, it should be apparent that the present invention includes new and novel compositions of matter and uses thereof not previously known in the prior art.